This episode covers the language of the hadith as well as some of the fiqh.
The ayah about wearing one's best clothes for the masjid is Surat al-'A'raaf 7:31:
Adorning Oneself for Prayer
What does 'faith' mean in the Revealed Law?
Introducing Shafi'i Fiqh (part 2)
The merit of La ilaha illa Allah